Conventionally, there is a known technique for cladding valve seats of a cylinder head in order to improve abrasion resistance and the like.
In the cladding, metal powder is molten by irradiating the valve seats with a laser beam and injecting the metal powder to the irradiated portion thereof, thereby the valve seats being partly coated with a metal different from the valve seats.
During the cladding, all of the metal powder does not adhere to the valve seats, and a surplus of the metal powder exists. If the surplus is allowed to stand, the surplus may enter gaps of parts and manufacturing devices, which causes trouble. Therefore, it is desirable to collect the surplus immediately.
Conventionally, various techniques for collecting the surplus of the metal powder during the cladding have been developed. For example, JP 2008-188648 A discloses one of the techniques.
In accordance with the conventional technique disclosed in JP 2008-188648 A, during the cladding of the valve seats using a laser cladding apparatus, the surplus of the metal powder and fumes are sucked to remove them from the valve seats.
Moreover, in accordance with the conventional technique disclosed in JP 2008-188648 A, a duct for sucking the metal powder and the fumes is provided with a filter to catch the sucked fumes and metal powder.
In the laser cladding apparatus, if air flow is increased to suck the metal powder, the metal powder to be attached to the valve seats is also sucked. Therefore, the air flow cannot be increased with no reason.
In the conventional technique disclosed in JP 2008-188648 A, the metal powder easily accumulates in a horizontal part of the duct, resulting in high frequency of cleaning of the duct.
Moreover, in the conventional technique, maintenance (replacement or cleaning) of the filter is frequently performed in order to avoid decrease in the air flow caused by clogging of the filter.
For this reason, it is difficult to improve operational efficiency when performing the cladding and collecting the metal powder.